1. Field of the Invention
The present invention relates to a switching element for use in an integrated circuit.
2. Description of the Related Art
An improvement in an arithmetic capacity of an integrated circuit is realized by an increase in a switching speed of transistors and an increase in the number of transistors in a chip. However, it is considered that miniaturization of transistors using silicon which is a key technology for realizing the improved arithmetic capacity will reach its limit in the near future.
Consequentially, in order to continuously develop the improvement in the arithmetic capacity of the integrated circuit, there have been investigated (A) development of transistors using a material other than silicon and (B) superimposition of transistors (realization of a three-dimension structure).
As to the former (A), transistors using carbon nanotubes, semiconductor nanowires or organic molecules has already been proposed, but there remain many problems to be solved.
For example, in regard to the carbon nanotubes, it is hard to regularly arrange them, and a process yield cannot be improved. Further, in case of transistors using a material other than the carbon nanotubes, a switching speed itself is lower than that of transistors using silicon.
As to the latter (B), it is hard to constitute multiple layers of silicon required to form transistors. Although a technology which realizes a three-dimensional structure by bonding a plurality of silicon substrates has been proposed, adopting this technology results in an increase in a cost.